Monopack process



' MoNoPAcK PnocEss Filed Ag. 1o, 195:5

y WMMW Patented Mar. 5, i935 MoNorAcK raocEss y Leonard T. Troland,deceased, late oi Cambridge,

Mass., by Cambridge Trust Company, Cambridge, Mass., executor, assignerto Technicolor Motion Picture Corporation, Hollywood, Calif., acorporation of Maine Application August 10,

11 Clas.

In certain branches of the photographic art, especially in colorphotography, emulsions are sometimes used which bear differentphotographic records in distinct layers or strata thereof. Films orplates of this type are usually termed monopacks, and various methodshave been proposed -to separate the records that are superposed in thesemonopacks. For example, a master' positive can be made from thesuperposed records, for example two color separation negatives madeaccording to the methods disclosed in the inventors Reissue Patent No.18,680, entitled Color photography, dated December d, 1932.Subsequently, the outer image can be chemicallyA eliminated asAdescribed and claimed in the inventors copending application Serial No.477,873, flled August 26, 1930. The master positive and the remaininglower negative record can then be superposed in register, and aso-called duplicate negative printed therefrom. This duplicate negativerepresents the lphotographic equivalent of the removed outer negativeand can be used together with the remaining original negative Vlike anyother pair oi color separation negatives. It will be apparent to any oneskilled in the art that this method can also be employed wii emulsionscontaining more than two recor y No matter whether the separation of thesuperposed monopack records is accomplished according to theafore-.mentionemor other heretofore proposed methods, the resulting setof separated records is imperfect due to the fact that it is practicallyimpossible to give to the inner and outer record layers (that is, thestrata adjacent to, and removed from the common support,y

respectively) equivalent treatments subsequent to exposure, so that thenal records do not correspond to an equal degree to the exposures whichthey received. The diiiiculty of imparting equal treatment to the layersis due to the inuence which the outer record exerts upon the diiiusionproperties of the agents used for developing the latent silver haliderecords, which properties-include all penetration and distributioncharacteristics Within the emulsion. 'Quite frequently, portions of aninner record which lie directly beneath heavily exposed parts of theupper record receive less development than portions underneath lightlyexposed portions of the outer stratum, so that in eiect a positiveimage'corresponding to the outer record is impressed upon4 the inner record.It is possible somewhat to mitigate this effect by making thedevelopment as complete as possible, butit is very Vdiiiicult by aheavily exposed part of the upper record,

1933, Serial No'. 684,545

and often impossible to eliminate it completely. It the main object ofthe present invention to rectify the above-described inuence of an outerrecord of a monopack upon an inner record thereof. Another object is theelimination of an 5V outer record by a chemical process in a quick,inexpensive and reliable manner by rectifying, at the same time, thedetrimental influence of the outer upon the inner record, exerted duringthe preceding development process. 10

These, and other objects of the invention will be'apparent from thefollowing description illustrating the genus of the invention bydescribing a concrete embodiment thereof. The

description refers to a drawing which represents 15` a ow` diagram withschematical lm cross sections illustrating the steps of the process.

It has been found that the above-described undesirable iniluence of theouter record upon the lower emulsion stratum, during devel- 20 opment',can be neutralized by a controlled reduction of both records with anagent which diffuses into4 the emulsion in a similar manner as thedeveloping agent, but acts chemically in the opposite sense, andtherefore undoes the un- 25 desirablegeect of the developer. In otherwords, the emulsion is treated with an agent which reduces thephotographic density of the portions of the lower record which,v duringdevelopment, have not been influenced by the other record, 30 and whichare `in most cases purposely overdeveloped, to an intensity whichapproximates that of the other portions of that record, that is, thoseportions' whose development was retarded by the outer record. The termreducing 3 is in this connection not employed in its chemical sense, butin its photographical meaning, which implies the diminution of themetallic silver contents of a photographic record. Preferably thistreatment is connected with a chemical 4.0 elimination of the upperrecord, using an agent which irst bleaches the outer record and thenbegins to reduce or bleach the inner record in the same manner, whereby.the eiect of the outer recordA upon the inner record has the same ex-45 tension but the opposite algebraic sign as compared with the effectof the developer. The reduction ofthe inner record is more eiective inparts where the developer has not been retarded that is, at the lighterdensities of the upper record, Where both developer and reducer candiffuse more' readily. In order to obtain this effect in the bestpossible manner, the diiusion relationships during reduction shouldoperate physically v'in the same manner as during development, whereaschemically, the record reducing effect should be arithmetically oppositethe preceding recordproducing effect of the developer. The better theseconditions are fulfilled, the more perfect is the corrected innerrecord.

In this manner the unfavorable eiect of development is eliminated,together with the removal of the outer image. Sometimes, it isadvantageous to employ the reducer also for correcting the excessivedensity of the inner record, (which is often a consequence of the forceddevelopment generally used in suchv processes), by carrying the reducingaction somewhat iurther as necessary for correcting the developmenteffect.

In carrying out this invention, any photographic reducer having theabove described physical and chemical properties can be used, butferricyanide or persulate reducers have been found to be particularlysuitable, and an embodiment utilizing such a reducer will now bedescribed.

The exposed monopack, as shown at A of the flow sheet, comprises asupport S, an upper latent record U, and a. lower latent record L indifferent strata of the emulsion E, these latent images beingsubstantially undistorted records of respective color aspects which isindicated by uniform shading of the exposed portions (high lights) ofthe two strata. After development, the silver records are distorted, asindicated at B, where the portions K of lower record L' are shown as oflower density than the remainder H of record L', due to the shieldingaction of those portions of the upper record which overlap with K,thereby somewhat delaying diffusion of the developer through U into L.It is evident that K is in eiect a positive impression of record U uponrecord L.

After development and the customary subsequent treatment which mayinclude nxation, the nlm is placed in a bath of an approximately 15%solution of potassium ferri-cyanide (or a weak solution of Farmersreducer, about 3% to 4%), where it remains until the upper record hasdappeared entirely, and the lower record is corrected by elimination ofthe impression thereon of a positive of the upper record, which takes,in normal cases, approximately 5 to 10 seconds, whereupon the lm isgiven a. very short rinse in water of about room temperature which hasthe purpose of removing the ferri-cyanide from the lm surface, andnnally bathe the hlm in a 40% solution of sodium thiosulfate. The illmhas then a structure as indicated at C, the outer record beingeliminated from upper emulsion stratum M and the inner record N being ofcorrect density, without any impression of the outer record.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modiiicationsand equivalents which fall within the scope of the appended claims.

It is claimed:

1. The method of separating superposed photographic records on the sameside of a nlm which comprises developing the latent records, andsubsequently bleaching the outer record and correcting the detrimentaleiect of the outer record upon the inner record during4 development, bytreatment with a photographic reducer whose diiiusion characteristicsare similar to those of the developer,

of the object iield,`

2. The method of treating monopack lms which comprises developing thesuperposed latent records of said hlm, bathing the film in an agenthaving a ditusion substantially equal to that of the developer andaffecting photographic records in a sense algebraically opposite to theaction of the developer, and interrupting the action of said agent uponelimination of the eiect of an outer record of said nlm upon an innerrecord thereof, during development.

. 3. The method of separating the superposed photographic records of amonopack nlm which comprises development of the latent recordsthereof,whereby the outer record is impressed upon the inner recor subsequenttreatment of said nlm in a solution of potassium ferri-cyanide until thecomplete outer record and the impression of the outer record upon theinner record are substantially eliminated, an immediately followingshort rinse in water, and subsequent xation.

4. The method of separating the superposed photographic records of amonopack nlm which comprises development of the latent records thereof,whereby the outer record is impressed upon the inner record, subsequenttreatment of said nlm in Farmers reducer until the complete outer recordand the impression o! the outer record upon the inner record aresubstantially eliminated, an immediately following short rinse in water,and subsequent nxation.

5. The method of compensation for the influence during developmentoi' acertain record of a nlm upon a separate and substantially coextensivesecond record of the same nlm which comprises the step ofphotographically reducing said second record with an agent havingdiffusion characteristics substantially similar to those of thedeveloper.

6. The method of compensating for the innuence of an outer record of amonopack nlm upon an inner record of the iilm during development, whichcomprises the step of controlled photographic reduction of said innerrecord with an agent having a diiiusion substantially equal to that ofthe developer.

'1. The methodof compensating for the influence during development of acertain record of aiilmuponaseparateandsubstantally coextensive secondrecord imderneath thereof on the same nlm, which comprises developmentof both latent records, and subsequent treatment withanagentwhichphysicallypenen'ates thelmin a manner similar to that ot thedeveloper, but whose eiIect upon the density of a photographic record issubstantially oppositeto that o! the developer.

A8. The method of separating the photographic records of `a miopack nlmwhich comprises developing the superposed latent records, making amaster positive of the superposed negatives, treating the nlm with aphotographic reducer having diffusion properties similar to those of thedeveloper lmtil the outer record is bleached and the eiIect of the outerrecord upon the inner record during development is eliminated, andmaking a duplicate negative of said bleached record by copying saidmaster positive and said inner record in simerposed registered position.

9. The method of separating superposed photographicrecordsonthesamesideof a iilmwhich comprises developing both records, andsubsequently photographically reducing the lower record under control ofthe upper record, to a degree substantially eliminating the eect of theupper record upon development of the lower record.

I0. 'Ihe method of separating superposed photographic records on thesame side of a nlm which comprises substantially overdeveloping bothrecords, and subsequently photographically reducingthe lower recordunder control of the upper record, to a degree substantially eliminatingthe effect of the upper record upon development of the lower record.

ll. 'Ihe method of separating superposed photographicrecords on the sameside o! a nlm which comprises developing the latent records until theyare substantially overdeveloped, the lower record receiving a reducedamount of development underneath the upper record commensurate to theretardation of the developer by said upper record, and photographicallyreducing said records with an agent being retarded substantially likesaid developer `until said upper record is substantially bleached andsaid lower record is brought to a. density approximately conforming toits latent state by said reducing action as controlled by theretardation eected by said upper record similar to the retardation ofthe developer.

' CAMBRIDGE TRUST COMPANY, Executor of the Last Will and Testament ofLeonard T. Troland, Deceased.

By A. MEAD WHEELER,

Its Asst. Secy.

